Aluminum nitride (AlN) has the characteristics of high strength, high volume resistivity, high insulation withstand voltage, coefficient of thermal expansion, and good matching with silicon, etc., not only as a sintering aid or reinf orcing phase for Structural Ceramics, especially in the field of ceramic electronic substrates and packaging materials that have been on fire in recent years, and its performance far exceeds that of alumina.
Among the important properties of aluminum nitride, the most significant is the hig thermal conductivity. Regarding the thermal conductivity mechanism of aluminum nitride, a lot of research has been done at home and abroad, and a relatively complete theoretical system has been formed. The main mechanism is: vibration through lattice or lattice, that is, the transfer of heat with the help of lattice waves or heat waves. The results of quantum mechanics tell us that lattice waves can be processed as the motion of a particle, a phonon. Heat waves also have wave-particle duality. Heat-carrying phonons transmit heat through mutually restrictive and coordinated vibrations between structural radicals (atoms, ions, or molecules). If the crystal is an inelastomer with a perfectly ideal structure, the heat can be freely transmitted to the cold junction by the hot end of the crystal without any interference and scattering, and the thermal conductivity can reach a very high value. Its thermal conductivity is mainly controlled by crystal defects and phonon scattering by the phonons themselves.
Theoretically, the thermal conductivity of AlN can reach 320W/m.K, but due to impurities and defects in AlN, the thermal conductivity of the actual product is less than 200W/m· K. This is mainly due to the fact that the structural primitives within the crystal cannot have a completely strict uniform distribution, and there are always sparse and dense different regions, so the current-carrying phonons will always be disturbed and scattered during propagation.
